Conventionally, among the seats of the abovementioned kind, as disclosed for example from the undermentioned patent-related document 1, there is known a seat having a lighting device provided therein as a functional element, such that the lighting device is partly exposed in an outer surface of the seat, Also, known from another patent-related document 2 mentioned below is a seat having a cup holder provided in a seat cushion thereof as a functional element, such that the cup holder is exposed in an outer surface of the seat. These functional elements exposed in an outer surface of the seat also function to improve a design and ornamental aspect of the seat.